Purpose: This study aimed to study the effect of carbimazole on parotid acini. Materials and Methods: 20 adult albino rats were selected and divided into two groups: control group (GI) consisted of 10 rats received distilled water by intra-gastric intubation for 6 weeks and carbimazole group (GII) in which 10 rats received carbimazole dissolved in distilled water with a dose (1.35mg/kg bodyweight/once/day) by intra-gastric intubation for 6 weeks. Results: GI illustrated normal histological features of acini. Serous acini were apparently normal in size with pyramidal shaped cells with pyramidal shaped cells of apparently normal height surrounding narrow lumen with basally located nucleus and basophilic cytoplasm. Carbimazole group showed marked destruction in acini. Most of the acini were shrunken with consequent separation between the acini in some areas. Some acini showed apparent loss of cell height and apparent widening of their lumina. Statistical Results: GI showed higher mean area % of acini, compared to GII. The difference was statistically significant. Conclusion: carbimazole has destructive effect on parotid acini.